1. Field of the Invention
An aspect of the present invention relates to an organic light emitting display apparatus, capable of removing motion blurring and preventing deterioration in brightness and increase in consumption power, and a driving method thereof.
2. Description of the Related Art
In general, light emitting display apparatuses display images using emissive devices. Such light emitting display apparatuses are classified into inorganic light emitting display apparatuses having a light emitting layer made of an inorganic material, and organic light emitting display apparatuses having a light emitting layer made of an organic material.
In an organic light emitting display apparatus, electrons and holes injected into an organic thin film through cathodes and anodes are recombined to form excitons, and light having a specific wavelength is emitted from the excitons.
The organic thin film has a multi-layer structure including a hole transport layer, a light emitting layer, and an electron transport layer, in order to improve light-emitting efficiency. Also, the organic thin film includes an electron injection layer or a hole injection layer in order to improve injection efficiency of electrons or holes and distribute the electrons and holes uniformly.
Driving methods of the organic light emitting display apparatus are classified into a passive matrix method and an active matrix method. In the passive matrix method, lines are sequentially selected and driven using an organic light emitting display apparatus in which anodes and cathodes are formed in a manner to intersect each other. The organic light emitting display apparatus driven by the passive matrix method has a simple structure which can be easily implemented. However, such an organic light emitting display apparatus consumes a large amount of current when driving a large screen, and a driving time of each light emitting device in a frame is short.
The active matrix method controls the amount of current which flows through respective light emitting devices, using active devices. The active devices may be thin film transistors (TFTs). The active matrix method consumes a small amount of current and has a long light emitting time, however, this method has a problem of motion blurring.
Motion blurring or blurring motion is a phenomenon in which pictures overlap or appear blurry when they move on the screen. The blurring motion affects organic light emitting display apparatuses and liquid crystal display apparatuses driven by the active matrix method, but has no effect on impulse type display apparatuses such as cathode ray tubes (CRT).
In the case of the impulse type display apparatuses, as illustrated in FIG. 1, by momentarily displaying light corresponding to different amounts of brightness to each pixel, afterimages are reduced. Meanwhile, in hold type display apparatuses, as illustrated in FIG. 2, by continuously displaying light, corresponding to an amount of brightness required for display, during a constant time to each pixel, afterimages are increased.
In order to improve motion blurring of the hold type display apparatuses, an impulse type driving method similar to a CRT display method has been developed. FIG. 3 is a graph illustrating an example in which the impulse type driving method is applied to a conventional hold type display apparatus. Referring to FIG. 3, in the hold type display apparatus, black frame images are inserted between successive frame images in order to implement the impulse type driving method.
However, an average brightness of the entire screen is reduced by the amount of the inserted black frame images. To solve this problem, current flowing through light-emitting diodes is increased when moving pictures are driven, however, this increase in current also increases power consumption.